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Di- and Trifunctional Initiators Containing Pt−Pd μ-Ethynediyl Units for Living Polymerization of Aryl Isocyanides

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posted on 02.11.2004, 00:00 by Kiyotaka Onitsuka, Ken-ichiro Yabe, Nobuaki Ohshiro, Atsushi Shimizu, Reiko Okumura, Fumie Takei, Shigetoshi Takahashi
Multinuclear acetylide complexes containing two or three Pd−Pt μ-ethynediyl units were prepared as multifunctional initiators for the living polymerization of aryl isocyanides. The polymerization smoothly proceeded to give two- or three-armed polymers with narrow polydispersity indexes in quantitative yields. Trace experiments using gel permeation chromatography and 31P NMR spectroscopy as well as kinetics revealed that all the Pd−Pt μ-ethynediyl units acted as initiators for the living polymerization. The polyisocyanide chains with narrow polydispersity indexes were cleaved off from the multiarmed polymers. The reaction of chiral monomer produced polymers having two and three helical chiral arms. Kinetic study of the polymerization of the chiral monomer and comparison of the chiroptical properties of resulting polymers with those of polymers prepared with Pd−Pt μ-ethynediyl complex suggested that the helical chiral polyisocyanide arms did not exhibit intramolecular interaction.